Fluorescence-based logic gate for sensing of Ca²⁺ and F^- ions using PVP crowned chrysene nanoparticles in aqueous...

Polyvinyl pyrrolidone (PVP) crowned chrysene nanoparticles (CHYNPs) were prepared by using a reprecipitation method. Dynamic light scattering (DLS) and scanning electron microscope (SEM) studies indicate that the monodispersed spherical nanoparticles bear a negative charge on their surfaces. The bathochromic spectral shift in the UV-visible and fluorescence spectrum of CHYNPs from chrysene (CHY) in acetone solution supports the J- type aggregation of nanoparticles. The aggregation-induced enhanced emission of CHYNPs at 486 and 522 nm decreases by increasing the concentration of the Ca²⁺ ion solution. It can display an ON-OFF type fluorescence response with high selectivity towards Ca²⁺ ions aqueous medium. Furthermore, the in situ generated PVP-CHYNPs-Ca²⁺ ensemble could recover the quenched fluorescence upon the addition of fluoride anions resulting in an OFF-ON type sensor. The present method has a correlation coefficient R² = 0.988 with a detection limit of 1.22 μg/mL for Ca²⁺ in the aqueous medium. The fluorescence changes of PVP crowned CHYNPs upon the addition of Ca²⁺ and F^- can be utilized as an INHIBIT logic gate at the molecular level, using Ca²⁺ and F^- chemical inputs and the fluorescence intensity signal as output.